At the current pace of technological innovation, an electronic device purchased today will likely become obsolete within the next couple of years. This presents a frustrating dilemma to consumers. Rapid obsolescence is perhaps nowhere more apparent than in the personal computer market segment. With new generations of more powerful computers being released every six months to a year, a consumer is wary of paying a premium for a top-of-the-line computer system knowing that in less than a year's time the same computer will be considered old technology, available to consumers at less than half its retail price at introduction.
One way a consumer can protect their investment in a computer system is to purchase a system having a processor that can be upgraded. For example, a consumer could purchase a 486-based computer system operating at 66 MHz, and later, if more power is desired, upgrade their processor to, for example, a 100 MHz 486 processor. For desktop personal computer systems, a consumer may also be able to upgrade their 486 processor-based system to a more powerful, compatible, next generation processor such as a Pentium.RTM. processor, available from Intel Corporation. of Santa Clara, Calif. In this manner, some portion of a consumer's initial investment in their desktop computer system is salvaged because the consumer need only purchase a more powerful processor to upgrade their computer system rather than purchasing an entirely new computer system.
Unfortunately, mobile computer systems are not as easily upgradable. Mobile computer systems include, for example, notebook computers, laptop computers, and personal data assistants. In the interest of saving space, the processor, chipset, memory, and various other primary components of the mobile computer system are highly integrated. This high degree of integration makes upgrading any one component of the mobile computer system, such as the processor, technically challenging and expensive, particularly for an upgrade from one processor generation to the next.
For example, FIG. 1 is a prior art computer system in which processor 10 is coupled to and communicates with bridge 12 via host bus 15. Bridge 12 couples processor 10 to peripheral component interconnect (PCI) sockets 1, 2, and 3 by coupling host bus 15 to PCI bus 16. The PCI protocol is described by the PCI Local Bus Specification, Revision 2.0 (1993), and Revision 2.1 (1995). In addition, bridge 12 couples main memory 14 to processor 10 and to the PCI sockets, thereby enabling three-way communication between these components. Level-2 cache 11 is coupled to processor 10 by way of another bus. Clock source 13 provides fast and slow clock signals synchronized to each other. The fast clock signals are applied to level-2 cache 11, processor 10, and bridge 12. The slow clock signals are applied to bridge 12 and to PCI sockets 1, 2, and 3, to which PCI compatible external devices are coupled.
Upgrading processor 10 to a faster processor in the same processor family is simply a matter of removing the old processor and inserting a new processor into the same socket. Upgrading to a next generation processor family, however, is more involved. To effectively upgrade the computer system of FIG. 1 to a next generation processor family, level-2 cache 11, processor 10, bridge 12, and possibly clock source 13 may need to be replaced. Replacement of all of these components in a mobile system may wind up costing more than the system itself is worth. In addition, the interconnect routings between these components and their corresponding sockets may not support an upgrade.